RESUMEN
The Au17 gold cluster was experimentally produced in the gas phase and characterized by its vibrational spectrum recorded using far-IR multiple photon dissociation (FIR-MPD) of Au17Kr. DFT and coupled-cluster theory PNO-LCCSD(T)-F12 computations reveal that, at odds with most previous reports, Au17 prefers two star-like forms derived from a pentaprism added by two extra Au atoms on both top and bottom surfaces of the pentaprism, along with five other Au atoms each attached on a lateral face. A good agreement between calculated and FIR-MPD spectra indicates a predominant presence of these star-like isomers. Stabilization of a star form arises from strong orbital interactions of an Au12 core with a five-Au-atom string.
RESUMEN
A systematic investigation on structure, relative stabilities, dissociation behavior and bonding of the singly and doubly Ni doped boron clusters BnNim with n = 2-22 and m = 1-2, was carried out using density functional theory (TPSSh functional) calculations. Calculated results indicate that for n < 14, BnNim structures are generally formed by capping Ni atom(s) on the edge or the surface of the pure boron Bn frameworks. From n = 14, the Ni dopants exert stronger effects in such a way that the most stable isomers BnNim adopt the shape of the related double ring tubular boron structures. With n ≥ 20, the Bn double ring appears to possess a large enough volume to entirely enclose the Ni2 dimer. The B14Ni and B22Ni2 turn out to be remarkable species with enhanced thermodynamic stability with larger average binding energies along with surprising geometric structures. Their higher thermodynamic stability can be understood in terms of the MO energy levels predicted by a hollow cylinder model, and other electronic properties. The (2 0 2)-orbital derived from the model of particle in a hollow cylinder appears to play a key role in the stabilization of the boron double ring.
RESUMEN
A systematic investigation on structure, dissociation behavior, chemical bonding, and magnetic property of Cr-doped Cun clusters (n = 9-16) is carried out using the mean of density functional theory calculations. It is found that CrCu12 is a crucial size, preferring an icosahedral Cu12 cage with the central Cr dopant. Smaller cluster sizes appear as on the way to form the CrCu12 icosahedron while larger ones are produced by attaching additional Cu atoms to the CrCu12 core. The presence of Cr dopant obviously enhances the stability of CrCun clusters in comparison to that of pure counterparts. Exceptionally stable CrCu12 has an 18-electron closed-shell electronic structure, mimicking a noble gas in the viewpoint of superatom concept. Analysis on cluster electronic structure shows that the interplay between 3d orbitals of Cr and 4s orbitals of Cu has a vital role on the magnetic properties of CrCun clusters.
RESUMEN
Stabilized fullerene and tubular forms can be produced in boron clusters Bn in small sizes from nâ¼ 14 to 20 upon doping by transition metal atoms. B14Fe and B16Fe are stable tubes whereas B18Fe and B20Fe are stable fullerenes. Their formation and stability suggest the use of dopants to induce different growth paths leading to larger cages, fullerenes and tubes of boron.